Turn key and a horrible grinding noise happens and will not start

Sounds as if the starter is spinning before it is engaging into the drive plate or teeth on the drive plate are worn to the point that the starter is not engaging and just grinding the away. Pull the starter and inspect the drive plate teeth. If they are worn in one section the transmission will have to come out to replace the drive plate, and the starter should also be overhauled or replaced. The engine stops on a compression and as the engine wears often one compression will be higher than the others and the engine will often stop on this point, so the starter works in the same starting position more often then others. This can eventually cause this problem.